Apparatus for smelting oxide ores



p 28, 1954 E. s. POMYKALA 2,690,333

APPARATUS FOR SMELTING OXIDE ORES Filed April 15, 1951 5 Sheets-Sheet lFig.1

INVENTOR p 28, 1954 E. s. POMYKALA 2,690,333

APPARATUS FOR SMELTING OXIDE ORES Filed April 13, 1951 3 Sheets-Sheet 2L5 5p9 5,03 INVENTOR E. s. POMYKALA 2,690,333

APPARATUS FOR SMELTING OXIDE ORES Sept. 28, 1954 3 sheets sheet 3 FiledApril 13, 1951 6 I 3 S2 IEVENTQR Patented Sept. 28, 1954 UNITED STATESATENT OFFICE 4 Claims.

This invention relates to method and apparatus for smelting iron andother metals and converting the blast furnace exhaust gases aftersuitable treatment into ammonia and other useful chemicals. It isprimarily devised for smelting iron particularly for localities wheresuitable coking coal is not readily available but where other fuels suchas natural gas or oil are plentiful. However, it is not limited tosmelting, it may be used to advantage as a step in the manufacture ofammonia, methyl alcohol, and other chemicals.

At the present time smelting of iron is done almost exclusively by meansof coke. The process consists in blowing highly preheated air throughblast pipes called tuyeres into the lower part of a high furnace orstack (about 100 feet high) filled with ore, coke, and a flux, generallyof limestone. In the lower part of the furnace opposite the tuyres, thecombustion is intense and temperatures are very high, about 2000 C. andthe burden of the furnace at this point is mostly glowing coke, and alittle slag and iron in liquid form precolating down. The ore in generalis reduced at a point above this level. The ore is reduced mostly bycarbon monoxide gas which is formed by combustion or chemical union ofhot glowing coke and a blast of air. In the lower part of the stack thetemperatures are so high that carbon dioxide (CO2) usually formed incombustion of coke can exist only momentarily and is immediately reducedby glowing carbon to carbon monoxide (CO). This may be expressedchemically as follows:

The reduction of iron ore is automatically carried out in stages.

(1) takes place in the upper part of the stack and (3) takes place inthe hotter part of the stack, lower down approximately at one half theheight of the stack above the tuyres. Below this point the reduction isaccomplished mostly by carbon alone. All this is somewhat simplified assome of the equtaions are reversible depending on temperature conditionsand there is some slight temporary oxidation taking place as the oreburden works down.

In the smelting of iron coke has a multiple function.

(1) Coke, by its combustion furnishes heat for the process.

(2) By its combustion, or chemical union with air it forms carbonmonoxide (CO) gas, which is the main agent used in reduction of ore.Coke or carbon together with carbon monoxide also protect the reducediron from oxidation by the blast air.

Finally coke has the important function as a load carrying mediumsupporting the overburden of ore and fluxing stone in the furnace.

All these functions are important, but it is felt they may beadvantageously separated to a considerable extent and some of thesepowers of coke be assigned to other fuels such as hot gasified petroleumderivatives like ethane, CzI-Is; propane, CaHs; butane, C4H10; pentane,C5H12; etc., or natural gas which is mostly methane, CH4, and theunsaturated hydrocarbons like ethylene, propylene, butylene or variouscombinations of these fuels.

It is the main object of this invention to show how this may be done.

It is well known that in the production of industrial gases such asproducer gas or water gas, hot steam may be reduced by glowing carbon tohydrogen and carbon monoxide the reaction being:

Both hydrogen and carbon monoxide incidentally are excellent reducingagents. However, to secure them it is proposed to blow not hot steamupon glowing coke, but hot hydrocarbons such as gasified petroleumfractions or even hot natural gas. This of course, cannot be done in ahaphazard manner, as such gases are very explosive if not properlyhandled, and one of the principal objects of this invention is to showhow this process may be carried out with safety.

Since in the operation of this new process for smelting iron and otherores, considerable carbon monoxide and hydrogen will flow out of thefurnace with the exhaust gases which will still consist mainly ofnitrogen. It is the further purpose of this invention to utilize theseexhaust gases in the manufacture of ammonia, methyl alcohol, and otherchemicals resulting therefrom.

In the operation of this new process coke will still be required, but inconsiderably smaller amount than at present, only about 40% of thepresent requirements will be necessary. Smaller amount of fluxing stonewill also be required since the amount of impurities needing fiuxingwill be less.

Another object of this invention is to improve the quality of theproduct manufactured namely, to reduce the carbon content in the smeltediron.

With these and other objects and advantages in view, the details ofconstruction and operation are further illustrated by having referenceto the accompanying drawings wherein:

Figure 1 is a general schematic plan and arrangement of the apparatus.

Figure 2 is a sectional plan of the blast furnace or smelting stacktaken on lines 2-2, in Fig. 3, approximately at the elevation of thetuyeres.

Figure 3 is a vertical section of the lower part of the blast furnacetaken on lines 3-3, in Fig. 2.

Figure 4 is a horizontal section of a tuyere taken on lines d l in Fig.5.

Figure 5 is a vertical sectional view of a tuyere taken on lines 55 ofFig. 4.

Figure 6 is a general sectional view of a blast furnace.

In all views similar numerals or numerals and letters designate similarparts.

Designations la, lb, and lo indicate retaining walls in the storagearea.

2 is a general storage area for ore, coke and limestone.

3a, 3b, 3c are railroad tr czs used for general transportation ofsmelting burden.

d is a chain conveyor used for delivering sme1ting burden from the binsor storage into the fur nace.

Numeral 5 indicates the blast furnace.

Now starting at the oth r end, numeral 6 indicates main oil feed line; iis a valve in the line; 8 is an oil pump; 9 is another valve on theoutlet side. H3 is heating coil or suitable heat exchanger, i2 is anoutlet valve, it is a hot hydrocarbon gas receiver, Etc is a gastemperature indicator, E3?) is a gas pressure indicator, i is a gasrelief valve, and it is suitable piping for gas relief purposes. Numeralit indicates main outlet valve for gas from the receiver is into mainsupply line 20. ll is a receiver or storage tank for nitrogen or othersuitable inert gas. it is a valve in line is controlling the flow ofnitrogen from receiver ll into main supply line Main supply line 253feeds the hot hydrogen gas into suitable bustle pipe shown in Figures 3and 6. From bustle pipe 570 the hot hydrogen gas is led through gooseneck pipe 51 into tuyeres 5p whence it is dischargedinto the furnace onglowing coke of the furnace charge, through aperture The heated aircomes from the air heating stoves through rnain feed line '28, intolarge bustle pipe whence it is directed through goose neck pipes 'Eininto combined tuyeres The hot air and hydrocarbon blast is dischargedinto the furnace on glowing carbon through apertures 5 95 and As inexisting practice there are a multiple number of tuyeres, generallyabout twelve units for a standard size furnace.

The furnace 5 in general follows present standard practice, except forthe double bustle pipe, special tuyeres, combined for leadinghydrocarbon gas together with standard air blast, and a specialconstruction for the bottom of the furnace at the crucible for giving abetter support to the overburden than is the practice at present.

The blast furnace construction is shown in Figure 6, and the details areshown in Figures 2, 3, 4 and 5.

In the construction of the crucible a departure is made from the presentpractice, inasmuch as cross walls to are built in and a ledge ii? isprovided around the periphery of the crucible. These are arranged in ahoneycomb fashion but may follow other patterns. All cross walls areinterconnected through holes for discharging molten ported partially onthe converging walls of the bosh (which is that part of the furnacedirectly above the crucible) and partially on the bottom. The coke tendsto dome over or arch over to the converging walls of the bosh butbecause of the large spans and also because a great deal of colic isconsumed here there is a slippage and a considerable amount of cokebelow the lines of eouilibrium falls and is pressed down into thecrucible. This is undesirable since in this manner coke comes in contactwith, and saturates the -molten iron.

It has been found that iron freshly cruel-ted as it percolates downthrough the glowing coke has a carbon content of about 1 percent. Afterit is in contact with carbon in the crucible the percentage of carbon israised to about e2 percent. This is not good since nearly all thiscarbon has to be burned out in making steel, either in the Bessemerconverter or Siemens open hearth furnace. This processing is quiteexpensive. By placing these cross walls so, as shoen in Figure 2, 3 and6 the spans of any domes of coke are greatly lessened. This is shown asE? in Figure 6. Lines of stability are more easily maintained and thelittle of the coke that falls below floats in the molten slag which isindicated by the boundary line x-az, between the slag and molten iron inFigures 3 and 6. By so doing, contact of coke with molten iron isminimized, and saturation of iron with carbon is avoided.

The remainder of the details of the furnace follow standard practice. InFig. 2, 50 are walls of the furnace at the bosh, are structural bands atthe bosh. Eie are structural bands at the crucible. 5g is outlet holefor molten metal, 5b is slag hole, 52' is a concrete slab foundation, 5;are wall cooling plates. {is (Fig. 6) are struc aural columns supportingthe main walls of the furnace.

In the upper part of the furnace 573 is the chute for loading the burdenof the furnace. This burden of coke, ore, and flux is lifted by means ofa chain conveyor 6 (Fig. 1) and deposited in chute 5t, whence it islowered by stages into the furnace by means of movable bells, 5a andthe. to is a working platform.

In construction of the tuyeres 5p a departure is made from the existingpractice. Where formerly it was one Water cooled blow pipe, it now hasthree apertures or nozzles, one for hot hydrocarbon gas and hot airmixture 5116, two for hot air blast 5175. Part of the preheateddelivered to nozzles 5105 passes through apertures 51:19 and mixes withthe hydrocarbon gases in nozzle 5106 and the resulting mixture thenpinges on the glowing furnace charge. The zles are made from one castingor forging and surrounded with a continuous wall The whole is so builtthat it is water-tight, bctween 5134 and walls Epl. There is a waterspace 5102, for circulating cooling water. 5123 are space lugs. 5:01 iscooling water inlet and cps is water outlet.

The gases discharged from the furnace are handled in a standard manner.They are discharged to main exhaust pipe or downcorner 2i, and are ledinto dust catcher 22. From there they are led by pipe 23 into a batteryof dust precipitators, 2d, thence through another duct 25 which leads apart of the hot gases into regenerative stoves 26a, 26b, 26c, 2601. Herethe exhaust gases are burned, heating the walls of the stoves to a hightemperature. After this heat extraction these gases are discharged, anda blast of air is circulated through the stoves by means of air fans orblowers 21a. and 2122. This air is preheated to a temperature of about1200 F. (650 0.), and is then redirected to the furnace through main airfeed line 28.

Since only a part of the exhaust gases are used for heating the stoves,the remainder of the gases can be put to other uses such as power orpreferably making chemicals. This will be shown later.

Opcration.ln the operation of this process, the furnace is loaded withsmelting burden as at present. The fires are started exactly the same,and the furnace is brought up to smelting on air blast alone, at about12 lbs. per square inch gage pressure. As this is taking place thegeneration and heating of hydrocarbon gas is started. This in generalfollows existing practice in the petroleum industry for making gasoline.Gasoline in the modern practice is largely made from heavier stock likepetroleum generally by one of several cracking processes. The base stockis heated either in the liquid state or injected into a heated chamberin the vapor state and in contact with a suitable catalyst whereby theheavier molecules are broken down into smaller units. The generalapproximate and typical equation being as follows: 700 C.

In my new process, great precision is not required and a greater varietyof size of molecules can be used. What is required is a; hot hydrocarbongas about 1200 F. (650 C.), and at approximately 12 pounds gagepressure. Small molecular size is desirable but not essential mainlysince gas of smaller molecular structure causes less expansion in theproducts of combustion. This heating and cracking process can beperformed in a hot coil I and a heated chamher is operating in theneighborhood of the temperature and pressure indicated above.

When the smelting furnace is well heated and operating on full blast, itmay then be switched over to hydrocarbon gas fuel. This is done in thefollowing manner: The lines 20 conducting the hot hydrocarbon gas fromthe receiver I3 have to be first flushed with inert gas preferablynitrogen, stored in tank ll. Nitrogen gas can be secured and purifiedfrom the exhaust gases issuing from the regenerative heating stoves 20ato 26d inclusive by a process shown in my U. S. patent applicationSerial No. 148,492.

After the lines are flushed, the hot hydrocarbon gas can be let inthrough valve it. As valve [6 is opened, the nitrogen valve I8 isclosed. The hydrocarbon gas is forced in the lines at 12 pounds persquare inch gage pressure. This hot gas drives out the nitrogen and isforced into the furnace through tuyres p. Just before issuing from thenozzle 5133 it is mixed partially with the air blast which is blown atslightly higher pressure than the hydrocarbon gas. This mixing is doneby means of apertures 5p0 and the hydrocarbon gas is burned partially atthe tip of the nozzle 5175. Because the mixing of the gases isincomplete in the nozzle and also because there is a shortage of oxygenat the tip of nozzle Epfi,

combustion is incomplete here. The generally accepted theory forcombination of hydrocarbons is that they first burn to alcohol and bystages break down to aldehydes and carbon monoxide, Water vapor andfinally carbon dioxide. However, as stated above due to the hightemperatures existing in the furnace at this point and in the presenceof glowing carbon, carbon dioxide and water vapor the usual end productsof combustion of hydrocarbons cannot exist and if they do it is onlymomentarily for they are immediately reduced by glowing coke to carbonmonoxide and hydrogen. The end average result that may be expected sayfor methane gas would be:

(a) CH4+ /2O2- 2H2+CO+ 6,620 cal. per gram mole with additional carbonof the coke bed.

(12) C+ A2O2+CO+28,800 cal. per gram mole Adding Equations a and b theresult is as follows:

CH4+C+O2=2H2+2CO+ 35,420 cal. per gram mole This indicates that thetemperature at the tuyeres with this new process will be less than underexisting process. However, the interior temperatures will be higher onaccount of the higher heat content per gram in the hydrocarbon over thatin the coke.

CH4+2OL=CO2+2H20+13,200 cal.

C+O2=CO2+8100 cal.

There are other reasons why higher temperatures may be expected in theinterior of the furnace above the tuyeres than at present. Considerableamount of ferrous oxide FeO will be re duced by hydrogen rather thancarbon.

From the above it would appear that there would be some increase intemperature in the interior of the furnace with this new process.However, high specific heat of hydrogen works against this increase anda considerable part may be nullified. This use of hydrogen in smeltingiron should have other useful benefits however, particularly it wouldtend to keep the carbon con tent in the iron lower than at present. Alsoit is possible that the process may lend itself to reducing other oreswhich are difiicult to smelt at present.

In the interest of safety it is necessary to consider the expansion ofthe gases in the furnace under the two methods. Under the existingmethod it may be assumed that coke in the vicinity of the tuyeres burnswith oxygen of the air blast to carbon monoxide.

20- -02+snen-z=zoo+avsm Solid-P1 vol.+3.'76 vol.=5.70 volumes Volumeincrease=g =l.35

The temperature of the gas increased as before. Total volumeexpansion=1.35 2.46:3.3.

From this it is seen that expansion is not abnormal and well withincontrol. Also in the interest of safety it may be mentioned that pipelines from hydrocarbon receiver to the furnace should always be flushedwith nitrogen whenever the furnace is being closed down, the operationbeing similar but in reverse to that when starting the furnace onhydrocarbon gas.

The gases as they issue from the top of the furnace will containnitrogen as the main component, as well as carbon monoxide, carbondioxide, hydrogen and Water vapor (steam) These can be treated bysuitable processes some existing and some recently devised (like theprocess shown in my U. S. patent application Serial No. 148,492) wherebyall the gases except nitrogen and hydrogen are eliminated and forming ammonia from these two. Also by existing systems.

CO+H2O=CO2+H2 Catalyst CO2 can be eliminated by process shown in patentapplication Serial No. 148,492. The remaining gases, nitrogen andhydrogen in proper pro-- portion and under high temperature and pressurecan be made to combine to form ammonia by various modern processes likeHaber, Claude, etc.

From ammonia other important industrial chemicals may be made. Theeconomic advantages using this method are: the vast supply of cheap rawmaterials and fairly low temperatures of the exhaust gases permit easyand eificient separation.

Methyl alcohol can also be made from these exhaust gases by processesnow in existence.

The exhaust gases as noted above contain nitrogen, hydrogen, carbonmonoxide, carbon dioxide, water vapor and small amount of variousimpurities. Carbon dioxide, Water vapor and other impurities may beeasily washed out as noted above for ammonia. The remaining gases,namely, nitrogen, carbon monoxide, and hydrogen which are fairlyinsoluble in water remain. Ihese gases can be highly compressed andheated, and with the aid of a suitable catalyst carbon monformingmethanol:

CO 21-12 =C'H3 .OH

Catalyst Having described the general features of the process andapparatus of this invention, it is felt others skilled in the art maymake changes in arrangement of parts and details without departing fromthe spirit of this invention or the scope of the appended claims.

I claim:

1. An apparatus for smelting iron and other metal oxide ores with thesimultaneous production of reducing gases, which comprises a blastfurnace, a source of liquid hydrocarbons, means for cracking andgasifying said hydrocarbons, means for compressing and preheating air tohigh temperatures, tuyeres for introducing the cracked hydrocarbons andthe preheated air into the furnace, each tuyere having a centralhydrocarbon nozzle and a pair of air nozzles mounted in a commonstructure directly adjacent to and on either side of said hydrocarbonnozzle, said nozzles being provided with apertures positioned close tothe exit of the tuyre which connect the air nozzles with the centralhydrocarbon nozzle for mixing the cracked hydrocarbon gases with part ofthe air as the gases enter the furnace; said nozzles being soconstructed and arranged that the bulk of the air passes through the airnozzles to impinge directly on the glowing furnace charge at either sideof the hydrocarbonair mixture discharged from the central nozzle, acrucible at the bottom of said furnace provided with verticalinterconnected cross walls forming a honeycomb structure withinterconnecting passageways for supporting the overburden out of contactwith the molten metal, means for charging the furnace, an externalsource of inert gas, conduit means connecting said source with thetuyeres for flushing an inert gas through the hydrocarbon nozzles of thetuyeres through the conduit means when the furnace is started and whenit is shut down, means for recovering the reducing gases discharged fromthe furnace, and means for Withdrawing molten metal from the furnace.

2. In a furnace for smelting iron and other metal oxide ores, tuyerescombining in one structure a central nozzle for introducing preheatedhydrocarbon gases into the bosh of the furnace, a pair of air nozzlesmounted directly adjacent said hydrocarbon nozzle for introducingpreheated combustion air into the furnace, said nozzles being providedwith apertures close to the exit of the tuyere connecting the airnozzles with the central hydrocarbon nozzle so constructed and arrangedthat part of the combustion air, insufficient to produce completecombustion, passes through said apertures to mix with the h drocarbon inthe hydrocarbon nozzle while the remainder of the air passes directlythrough the air nozzles to impinge upon the furnace charge.

3. An apparatus for smelting iron and other metal oxide ores with thesimultaneous generation of reducing gases, which comprises a blastfurnace provided with a bosh and at the bottom with a crucible, meansfor supplying partially cracked hydrocarbon gases preheated to hightemperatures to said furnace, and for supplying compressed air preheatedto high temperatures to said furnace, said means comprising a pluralityof tuyeres mounted around the bosh of the furnace each tuyre having in asingle structure a central hydrocarbon nozzle and directly adjacent airnozzles mounted on either side of the hydrocarbon nozzle, said nozzleshaving interconnecting passageways so constructed and arranged as tocause a' portion of the air to mix with the hydrocarbon gases as theypass through the central nozzle in amount insufficient to pro ducecomplete combustion of the hydrocarbon gases while the bulk of the airpasses directly from said air nozzles into the bosh of the furnace toimpinge against the glowing furnace charge, vertical cross walls builtin the crucible at the bottom of the furnace and arranged in honeycombfashion for supporting the furnace charge out of contact With the moltenmetal in the cm cible and provided with interconnecting passageways fordischarging molten metal, means for charging the furnace, means forwithdrawing molten metal from the furnace and means for recoveringreducing gases discharged from the furnace.

4. The apparatus of claim 3 including an external storage chamber for aninert gas and con- 9 duit means connecting said storage chamber with thetuyres for flushing the inert gas through the hydrocarbon nozzles of thetuyres and through said conduit means when the furnace is shut down andbefore it is placed in operation.

References Cited in the file of this patent UNITED STATES PATENTS NumberNumber 10 Name Date Weber Sept. 1, 1885 Perkins May 7, 1907 Kemp Oct.12, 1909 Frick Dec. 5, 1911 Carstens Oct. 18, 1921 Ward Dec. 14, 1926Valentine Aug. 4, 1941 Hansgirg Dec. 28, 1943 Williams May 8, 1945Kinney May 13, 1947

1. AN APPARATUS FOR SMELTING IRON AND OTHER METAL OXIDE ORES WITH THESIMULTANEOUS PRODUCTION OF REDUCING GASES, WHICH COMPRISES A BLASTFURNACE, A SOUCE OF LIQUID HYDROCARBONS, MEANS FOR CRACKING ANDGASIFYING SAID HYDROCARBONS, MEANS FOR COMPRESSING AND PREHEATING AIR TOHIGH TEMPERATURES, TUYERES FOR INTRODUCING THE CRACKED HYDROCARBONS ANDTHE PREHEATED AIR INTO THE FURNACE, EACH TUYERES FOR INTRODUCING THECARBON NOZZLE AND A PAIR OF AIR NOZZLED MOUNTED IN A COMMON STRUCTUREDIRECTLY ADJACENT TO AND ON EITHER SIDE OF OF SAID HYDROCARBON NOZZLE,SAID NOZZLES BEING PROVIDED WITH APERTURES POSITIONED CLOSE TO THE EXITOF THE TUYERE WHICH CONNECT THE AIR NOZZLES WITH THE CENTRAL HYDROCARBONNOZZLE FOR MIXING THE CRACKED HYDROCARBON GASES WITH PART OF THE AIR ASTHE GASES ENTER THE FURNACE; SAID NOZZLES BEING SO CONSTRUCTED ANDARRANGED